Wind Power Wind Up?

[Sea Devil]

I was told yesterday that the wind in cold climates is denser than the wind in warm climates - Which is why the wind in UK waters of a given strength feels so much more powerful than the same wind in warm waters.

Must admit it feels like that but.... A wind wind up?

 

[snowleopard]

If I remember my school physics correctly, at a given pressure, the volume of a given mass of gas is in direct proportion to the absolute temperature. in other words the density decreases by 1% for every 3 degree celsius rise in temperature. A freezing wind will therefore have 10% more weight than a balmy 30 deg breeze.

 

[mikesharp]

From practical experience playing golf (my other hobby) a cold wind against has much more stopping power on a shot than a warm one.

 

[Rowana]

I have heard that aircraft develop more lift in colder air - Perhaps some of our flying types can comment ??

 

[AlexL]

no wind up.
the power generated by wind (for lift on aircraft, or any other airfoil sails, propellors etc) is proportional to the density, but also proportional to the velocity squared. So a small change in wind strength has a large change in 'lift', so the density effect is tiny in comparison.

 

[cozy]

Hot air is less dense than cold air. However, whether that alone is detectable by skin contact I'm not sure. Might have something to do with windchill and humidity.

 

[rwoofer]

However wind anemometers are susceptible to the same forces, therefore 20 knots indicated will feel the same whether hot or cold. The actual windspeed will differ though.

RB

 

[Vara]

Thats not right a rotating cup anenometer only measures wind speed,not its energy.

To do that you need a completely different instrument the one I saw was basically a square piece of wood attached to a load cell which was aligned to face the wind manually not used for met but for demonstrating graphically the relationship between wind speed and force.

 

[bobfrost]

Hate to be a pedant but:-

Both anemometers measure energy potential of the wind (i.e. power)

This varies in proportion to the cube of the wind speed AND is proportional to density of air.

For accurate measure you have to use radar which measures doppler shift of small particles e.g. dust, carried by wind.

 

[Sea Devil]

So after all that, does denser wind - cold wind - exert more force at a given wind strength on a sail than warmer less dense wind?

 

[Nauti Fox]

[ QUOTE ]
I have heard that aircraft develop more lift in colder air - Perhaps some of our flying types can comment ??

[/ QUOTE ]

I can only comment from personal experiance on piston engined aircraft but yes it is true. In the aircraft manual you get various graphs for air temp, height above sea level etc.
The biggest difference it does make though is to engine performance, most noticable on piston powered helicopters.

 

[bobfrost]

[ QUOTE ]
So after all that, does denser wind - cold wind - exert more force at a given wind strength on a sail than warmer less dense wind?

[/ QUOTE ]

Yes

 

[BobOwen]

Its one of the reasons performance cars use intercoolers. They reduce the temperature of the air charge entering the engine. Lower temperature, denser charge, more oxygen, more go!

 

[Sea Devil]

Thanks for that. Explains why I prefer to be in a gale in the Pacific rather than the English channel!